the protective
effects of MOS in crustaceans have been shown to be
associated with the granular cells having the ability to binding
to mannose and to be involved in triggering cellular and
humoral defense mechanism of this animal in response to a pathogenic challenge. The bacterial clearance as a summative
measure of humoral and cellular defense capacity and it
would be useful in rapid, preliminary screening of dietary
components for the potential ability to improve defense
capacity. The percentage of granular cells and the rate of
bacterial clearance for the yeast extract were higher than
those for shrimp fed the control diet (Srithunyalucksana et
al., 2005). The results of the present study indicated better
performance and improved resistance against diseases. This
may result from the effect of -glucan of the yeast cell wall
component, which has been reported to have immunostimulating
activity for shrimp